Kids who love maths

Let me make an assumption, you've all done your times tables. And I'm guessing that some of you may have learnt this, but the majority of you have not. I am going to teach you how to multiply any 2 digit number by 11. So lets say that we take 36 as our two digit number. What is 36 * 11? To find out the answer, take these three steps: 1. Split the number into 2 seperate digits, so we have 3 and 6. 2. Add those together. So now we have 9. 3. Put your result in the middle of the original two numbers. So we get 396. A quick check on a piece of paper or a calculator will show you that 36 * 11 does indeed equal 396. But there is a problem. What if you tried 38 * 11? Well, 3 + 8 = 11 so the answer should be 3118 right? No. In this case (when the sum of the two numbers equals 10 or more), you must carry over the 1 to the 3 to make it a 4. So your answer is no 418. A check will show that it is in fact 418. There you go. You can now go and impress all of your friends with this ...

Hi guys, I'm back with a quick(or not so quick) math problem for you to solve. Remember, please try and solve it yourself, rather than waiting for me to post the answer. Anyway, here it is. The minute and hour hands are at angles of 180º(straight) a total of twelve times each twelve hours(approx. one per hour). What are the exact times where this occurs? Please put your answer in the comment section below and I will make sure to post the answer soon.

Hi, This is my first post on this blog, and to celebrate this occasion, I would like to do something special. As it is the 100th day of the year, April 10 2018 (just keep in mind that if it is a leap year, the 100th day of the year will be on April 9), I would like to give you √100 facts about 100. So, here we go: √1. In binary, 100 is 1100100, and in hexadecimal, it is 64. √4. 100! ends with 24 zeros. √9. The 100th most populated country in the world is Bulgaria (as of 2014). √16. 1 ³  + 2 ³  + 3 ³  + 4 ³  = 100 √25.  In Old Norse, the word hundrad, from which our ‘hundred’ derives, originally meant 120. √36. In Belgium, 100 is the ambulance and firefighter telephone number √49. 1 followed by 100 zeros is called a 'googol' and 1 followed by 1 googol zeros is called a 'googolplex'. √64. 100 is the sum of the first 10 odd numbers. √81. A sneeze travels at about 100 miles/hour (160.93 km/h). √100. 100 is the sum of th...

I'd like to take this opportunity to welcome my friend, and the brand new co-author of this blog, Noah B. You might remember him from a previous post where I mentioned his own blog rubiksmaniac.blogspot.com.au . I am glad to announce that he has stopped work on his blog to help with mine. Look forward to more posts from not only me, but also Noah. Also, don't forget to check out the programming pages. Noah and I will be updating them regularly. Yours in numbers, Lachlan

I know that it's a bit late, but this is a special after the recent ∏ day. For those of you who don't know, or simply can't remember, ∏ is the result of dividing the circumference of any given circle by the diameter of the same circle. For example, say you have a circle with a diameter of D. The circumference of the circle is ∏D. PI is an irrational number, meaning that it contains an endless number of digits. This offers a challenge to any with a good memory, and PI memorising competitions have been set up across the globe. These people have extraordinary memory. For example, I have memorised a total of seventy digits of PI, as shown below. 3.1415926535897932384626433832795028841971693993751058209749445923078164 This may seem impressive, but the Guinness World Record holder, Lu Chao of China, who broke the record in 2005, recited a total of 67890 digits. Whoever can post me a program generating digits of pi will be featured in a future post. Make sure that it is yo...

Recently I published a post on squaring numbers ending with five, but in this post, I'm going to take it a step further, and teach all the divisibility rules up to 13. Divisibility rules are the guidelines for working out if a larger number is divisible by your smaller one. They never make an error. Sadly, as there are infinite prime numbers, and therefore infinite divisibility rules, I can neither learn all of them, or teach you all of them. But chances are that you will ever need to know any above thirteen, so 'fire away!'. 1: All whole numbers are divisible by 1. 2, 4, 8, etc: To find out whether a number is divisible by 2^n, all you need to do is take the last n digits of the larger number is divisible by 2^n, or zero. e.g. 31242345840 is divisible by 8 (2^3), because the last 3 (n) digits, 840, is a multiple of 8. This is because any power of 2 (2^n) is a factor of the same power of ten (10^n). e.g. 16 (2^4) = 10000 (10^4) ÷ 625 (5^4). As you have just seen, yo...

In one of my earlier posts, I talked about the Maths Olympiad, a worldwide mathematics competition. I finished it off with an example Maths Olympiad problem from excellent.org. Here it is in its full glory. If x and y are real numbers satisfying             x 2 + xy = 20 and y 2 + xy = 30 what is the value of xy? Today I’m back to answer this problem. x² + xy = 20 y ² + xy = 30 ( x²  + xy) + ( y ² + xy) = 50 ( x²  + xy) x ( y ² + xy) = 600 ( ( x²  + xy) x ( y ² + xy)) ÷ ( ( x²  + xy) + ( y ² + xy)) = xy  ∴ 600 ÷ 50 = xy              = 12 Yours in numbers,  Lachlan